The Nobel Prize in Chemistry for 2012 was awarded jointly to American scientists Robert J. Lefkowitz and Brian K. Kobilka for "for studies of G-protein–coupled receptors" that shed light on how billions of cells in our body interact with their environment, the Royal Swedish Academy of Sciences announced Wednesday.

Lefkowitz started to use radioactivity in 1968 to trace the cells' receptors. His team of researchers extracted the receptor from its hiding place in the cell wall and gained an initial understanding of how it works. With the creative approach of newly recruited Kobilka, the team achieved its next big step during the 1980s. He isolated the gene that codes for the β-adrenergic receptor from the gigantic human genome.

In 2011, Kobilka achieved another breakthrough when he and his research team captured an image of the β-adrenergic receptor at the exact moment that it is activated by a hormone and sends a signal into the cell. “This image is a molecular masterpiece -- the result of decades of research,” a statement on the Nobel Prize website said.

Lefkowitz was born in 1943 in New York and obtained his M.D. in 1966 from Columbia University. Kobilka was born in 1955 in Minnesota and obtained M.D. in 1981 from Yale University School of Medicine.

Both the scientists will share this year's awards, which are worth 8 million Swedish krona ($1.2 million).

On Monday, the Nobel Prize in Medicine was awarded jointly to British scientist John B. Gurdon and Japanese scientist Shinya Yamanaka for their work in stem cell research.

The Physics Nobel was awarded Tuesday to French scientist Serge Haroche and American scientist David J. Wineland for their groundbreaking studies related to quantum systems.